A cycle-mounted vehicle proximity warning device warns a cyclist that a vehicle is approaching the cycle from the rear. A like device, worn by a pedestrian, warns the pedestrian of approaching vehicles. The warning device includes a vehicle detector circuit and an antenna that transmits and receives. The vehicle detector circuit detects a vehicle as it approaches the cycle or pedestrian and emits a detection signal. An alarm circuit responds to the detection signal and communicates an audible, visual, or tactile warning to the cyclist or pedestrian. The vehicle proximity warning device also includes a vehicle alert circuit that can activate a bright flashing light aimed at the approaching vehicle for the purpose of alerting its driver of the cyclist or pedestrian proximity.

Pedestrians and slow-moving vehicles such as bicycles, must often share roads and highways with many types of fast-moving vehicles. In many cases, the pedestrian or slow-moving vehicle may not be visible to oncoming traffic. The pedestrian or slow moving vehicle, may not be aware of the approaching high speed traffic. This is a situation that can easily result in a serious accident.
Bicycles are typical of slow-moving vehicles with high potential for being victims of accidents with faster vehicles. Bicyclists rarely move as fast as normal highway traffic. They often are not completely aware of their surroundings due to poor visibility, helmets, wind noise, varying terrain, and other environmental factors. Most cycling traffic accidents occur either because the cyclist did not anticipate the approaching vehicle (often from the rear) or the driver of the vehicle did not see the cyclist in time to take evasive action.
In addition to cyclists, there are many other potential victims of fast-moving vehicles both on and off the road. These include pedestrians, skiers, highway workers, roller-bladders, skaters, and other personnel that must use highways, roads, or trails where visibility may be limited. Larger vehicles with limited visibility, including motorcycles, horse-drawn vehicles, and farm vehicles, may also be involved in accidents with rapidly approaching vehicles.
To reduce the possibility of accidents, slow moving, limited-visibility vehicles, and pedestrians would be aided by a proximity detector that would warn them of oncoming traffic and make the oncoming traffic aware of their presence. A vehicle proximity-alerting device could help avoid many of these potential accidents and possibly decrease the morbidity and mortality of cyclists, pedestrians, and others.
There are a large number of possible applications for a proximity detector that would warn users of oncoming traffic and make the oncoming traffic aware of their presence. The following are some examples of slow-moving and/or low-visibility road users in need of a vehicle proximity-alerting device: motorized: motorcycles, farm vehicles, construction vehicles, mail delivery vans, buses; non-motorized: bicycles, skateboards, roller blades, scooters, skates, small battery-powered cars, infant strollers, horses, horse-drawn vehicles; and pedestrian: children, walkers/joggers/runners, and highway workers.
The following are some examples of slow-moving and/or low-visibility off-road users of a vehicle proximity-alerting device: motorized: airport equipment (baggage cars, tow truck, etc.), amusement park trams, motor boats; non-motorized: off-road bicycles, row boats, sailboats; and pedestrian: skiers, and construction workers.
One example of a practical application is be a vehicle proximity-alerting device for motorcycles. Motorcycle accidents involving other vehicles are often fatal to the motorcycle rider. Although a motorcyclist is usually alert to the presence of other vehicles, it is not always the case. Also, motorcycles are often not perceived by motorists. The xe2x80x9cMotorcycle Accident Cause Factors and Identification of Countermeasures,xe2x80x9d was a study conducted by the University of Southern California (USC). With funds from the National Highway Traffic Safety Administration, researcher Harry Hurt investigated almost every aspect of 900 motorcycle accidents in the Los Angeles area.
Additionally, Hurt and his staff analyzed 3,600 motorcycle traffic accident reports in the same geographic area. Some of the findings relevant to vehicle/motorcycle accidents from the report are summarized as follows:
1. Approximately three-fourths of these motorcycle accidents involved collision with another vehicle, which was most usually a passenger automobile.
2. In the multiple-vehicle accidents, the driver of the other vehicle violated the motorcycle right-of-way and caused the accident in two-thirds of those accidents.
3. The failure of motorists to detect and recognize motorcycles in traffic is the predominating cause of motorcycle accidents. The driver of the other vehicle involved in collision with the motorcycle did not see the motorcycle before the collision, or did not see the motorcycle until too late to avoid the collision.
4. Conspicuity of the motorcycle is a critical factor in the multiple vehicle accidents, and accident involvement is significantly reduced by the use of motorcycle headlamps (on in daylight) and the wearing of high visibility yellow, orange, or bright red jackets.
5. The view of the motorcycle or the other vehicle involved in the accident is limited by glare or obstructed by other vehicles in almost half of the multiple-vehicle accidents.
Applicants proximity-alerting device is designed to accommodate a wide range of applications. For some applications, the proximity-alerting device is designed for a specific application. For example, at night a pedestrian or road worker may not require as bright a warning light as a daytime user. For this application, it is be feasible to use flashed LEDs, thereby reducing power and weight so that the detector could conveniently be worn on a person""s back.
Applicant provides approaching-vehicle proximity-alerting device designed to alert both the oncoming vehicle driver and the user of the device. Such a device includes several components. A low-power radar or another appropriate detector determines vehicle proximity (by velocity and/or distance). A flashing light is produced by the device to alert the driver of the oncoming vehicle by stimulating his visual perception. Depending on the user application (pedestrian, bicyclist, etc.), the device includes an audible, tactile and/or visual signal emitter at the same time that the driver of the oncoming vehicle is alerted by the flashing light. The vehicle-detection, visual-alert, and audible-alert circuits control and timing circuits initiate the alert upon correct detection of a vehicle. The alert device may be incorporated into other equipment such as, music earphones, heart rate monitors, and ear protection devices. Power for all circuits is supplied by internal batteries or supplied by an external power source in some applications.
The detection circuits typically consist of a simple low-power continuous wave Doppler radar. Currently, a complete RF Doppler radar module based on GUNN diode technology can be purchased commercially for approximately $75 (MA/COM Model MA87728-MO1). A similar module has a planar array and printed circuit board The detector and additional electronics, including control circuits and output circuits (audible and visual), are typically provided as a single printed circuit board.
For some applications, the device power requirements reduce the duty cycle of one or more circuits. As an example, the duty cycle of a GUNN diode radar may readily be reduced by a factor of ten. The radar may operate for ten milliseconds and be in an off state for ninety milliseconds. During the ninety milliseconds off state, an oncoming vehicle traveling at one hundred miles per hour would close by only thirteen feet. For the GUNN module previously described, the normal detection range would be on the order of about two hundred feet. Reducing the duty cycle by a factor often would reduce the range less than 7%. Similar duty cycle reduction on the other circuits may also be appropriate for some applications.
Infrared radar is provided as an alternate detector, especially for night use. Infrared radars typically use solid-state infrared laser diodes and are known as LADARs. They generally use a semiconductor diode to generate laser light. Most vehicle traffic LADARS emit laser light at around 904 nm wavelength. Other wavelengths are possible; for example, aluminum gallium arsenide (AlGaAs) diodes emit light at a wavelength of 850 nm. Gallium arsenide (GaAs), classified as an injection laser, emits light between 880 nm to 900 nm. Other wavelengths are possible using other materials or alloys.
The Federal Communications Commission (FCC) regulates radiated emissions from high-speed circuits such as the processing circuits inside a LADAR, but not infrared and light frequencies. The Federal Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) regulates laser products sold in the United States. Traffic LADARs are Class 1 devices (by American National Standards Institute definition) and considered eye-safe based on current medical knowledge.
New ultra-wideband radar technology based on very narrow pulses has the potential for providing both range and speed information using very low power. Although not commercially available at this time, there is potential for use of ultra-wideband radar as the vehicle detector for a proximity-alerting device.


An apparatus may be communicatively coupled to other nodes in a network. The apparatus may include a control circuit configured to repeatedly issue transmission cycles to the other nodes. A given transmission cycle may include a least one send slot for each of the other nodes to send data. The control circuit may be configured to initiate transmission cycles by issuing beacon signals to the other nodes. The control circuit may be configured to determine when to issue a beacon signal in a given transmission cycle by determining that all of the other nodes have completed all associated send slots in an immediately previous transmission cycle and based upon a determination of the completion of the other nodes' transmission, delaying transmission of the beacon signal for the given transmission cycle.

10SPE is a proposed standard currently under revision and development. 10SPE defines Ethernet local area, access and metropolitan area networks. Ethernet is specified at selected speeds of operation; and uses a common media access control (MAC) specification and management information base (MIB). The Carrier Sense Multiple Access with Collision Detection (CSMA/CD) MAC protocol specifies shared medium (half duplex) operation, as well as full duplex operation. Speed specific Media Independent Interfaces (MIIs) provide an architectural and optional implementation interface to selected Physical Layer entities (PHY). The Physical Layer encodes frames for transmission and decodes received frames with the modulation specified for the speed of operation, transmission medium and supported link length. Other specified capabilities include control and management protocols and the provision of power over selected twisted pair PHY types.

EMI reduction in PLCA-based networks through beacon temporal spreading


Process for the preparation of a rigid polyurethane or urethane-modified polyisocyanurate foam in the presence of a hydrocarbon blowing agent using a tolylenediamine-initiated polyether polyol in an amount of between 10 and 40% by weight based on total isocyanate-reactive compounds.

This invention relates to processes for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams, to foams prepared thereby, and to novel compositions useful in the process.
Rigid polyurethane and urethane-modified polyisocyanurate foams are in general prepared by reacting the appropriate polyisocyanate and isocyanate-reactive compound (usually a polyol) in the presence of a blowing agent. One use of such foams is as a thermal insulation medium as for example in the construction of refrigerated storage devices. The thermal insulating properties of rigid foams are dependent upon a number of factors including, for closed cell rigid foams, the cell size and the thermal conductivity of the contents of the cells.
A class of materials which has been widely used as blowing agent in the production of polyurethane and urethane-modified polyisocyanurate foams are the fully halogenated chlorofluorocarbons, and in particular trichlorofluoromethane (CFC-11). The exceptionally low thermal conductivity of these blowing agents, and in particular of CFC-11, has enabled the preparation of rigid foams having very effective insulation properties. Recent concern over the potential of chlorofluorocarbons to cause depletion of ozone in the atmosphere has led to an urgent need to develop reaction systems in which chlorofluorocarbon blowing agents are replaced by alternative materials which are environmentally acceptable and which also produce foams having the necessary properties for the many applications in which they are used.
A class of materials which have been used as alternative blowing agents with zero ozone depletion potential are hydrocarbons especially alkanes and cycloalkanes such as isobutane, n-pentane, isopentane, cyclopentane and mixtures thereof. However thermal insulation properties of hydrocarbon blown rigid polyurethane foams are not satisfactory. Another disadvantage of hydrocarbon blowing agents is their limited solubility in the standard isocyanate-reactive compositions.
It is an object of the present invention to provide hydrocarbon blown rigid polyurethane or urethane-modified polyisocyanurate foams having improved thermal insulation properties.
It is another object of the present invention to provide a process for making hydrocarbon blown rigid polyurethane or urethane-modified polyisocyanurate foams whereby the solubility of the blowing agent in the isocyanate-reactive composition is improved.
These objects are met by using in the process of making rigid polyurethane or urethane-modified polyisocyanurate foams from polyisocyanates and isocyanate-reactive components in the presence of hydrocarbons as blowing agent a tolylenediamine(TDA)-initiated polyether polyol in an amount of between 10 and 40% by weight based on the total isocyanate-reactive compounds.
Foams prepared by the process of the present invention show better thermal insulation than foams from the prior art prepared not using tolylenediamine (TDA)-initiated polyether polyols. Further the solubility of hydrocarbon blowing agents in the isocyanate-reactive composition is improved by using TDA-initiated polyether polyols.
Aromatic amine initiated polyether polyols such as TDA-initiated polyether polyols and diaminodiphenylmethane or polymethylene polyphenylene polyamine (DADPM)-initiated polyether polyols have been described as suitable isocyanate-reactive compounds for hydrocarbon blown rigid polyurethane foams (see, for example, EP 421269, WO 94/25514, EP 708127, U.S. Pat. Nos. 5,523,333, 5,523,332, 5,523,334 and EP 617068). None of these prior art documents suggests an improvement in thermal insulation properties or in hydrocarbon solubility by using TDA-initiated polyether polyols instead of DADPM-initiated polyether polyols. WO 96/23017 and EP 747411 (both citable under Article 54(3) EPC) describe the use of TDA-initiated polyols in hydrocarbon blown rigid polyurethane foams in an amount of at least 40% by weight based on total polyols.
The TDA-initiated polyether polyols for use in the present invention are obtained by the addition of alkylene oxides, such as ethylene oxide and/or propylene oxide to one or more of the various isomers of tolylene diamine such as 2,4-, 2,6-, 2,3- and 3,4-TDA. Preferably 2,3- and/or 3,4-TDA (ortho-TDA or vicinal TDA) is used as initiator with up to 25 wt % of total initiator of meta-TDA (2,4- and/or 2,6-TDA). Vicinal TDA is a pure isomer or mixture thereof, preferably containing 20 to 80 wt % 2,3-TDA and 80 to 20 wt % 3,4-TDA. Other co-initiators can be used additionally in an amount up to 60% by weight of total initiator, preferably between 5 and 10% by weight. In a preferred embodiment aliphatic amines are not used as co-initiator.
The alkylene oxides used are preferably 0 to 90% ethylene oxide, more preferably 20 to 80% ethylene oxide and 100 to 10%, preferably 80 to 20% propylene oxide.
The TDA-initiated polyether polyols for use in the present invention generally have OH numbers in the range 200 to 700, preferably 250 to 550 mg KOH/g, more preferably between 350 and 520 mg KOH/g and have functionalities in the range 2 to 8, preferably 3 to 6. The molecular weight is generally between 400 and 700.
Tolylene diamine initiated polyether polyols and methods for their preparation are fully described in the prior art, for example, in U.S. Pat. Nos. 4,243,759, 5,141,968, 4,391,728, 4,421,871, 4,562,290, 4,469,822, 4,397,966, DD 272307, DD 251151, DD 290202 and DD 290201.
A preferred TDA-initiated polyether polyol for use in the present invention is a polyether polyol of OH value 300 to 400 mg KOH/g, obtained by reacting o-TDA (containing up to 25 wt % of m-TDA) with propylene oxide. The amount of TDA-initiated polyol is preferably between 10 and 39% by weight based on the total isocyanate-reactive compounds, more preferably between 10 and 35% by weight, most preferably between 20 and 33% by weight.
In the case of blowing with solely cyclopentane as hydrocarbon the amount of TDA-initiated polyether polyol is preferably below 35% by weight, more preferably below 30% by weight, most preferably below 25% by weight based on total isocyanate-reactive compounds.
The hydrocarbon blowing agents for use in the present invention are preferably (cyclo)alkanes, preferably containing from 3 to 8 carbon atoms, such as cyclopentane, isopentane, n-pentane, neopentane, n-butane, cyclobutane, methylcyclobutane, isobutane, propane, cyclopropane, methylcyclopropane, n-hexane, 3-methylpentane, 2-methylpentane, cyclohexane, methylcyclopentane, n-heptane, 2-methylheptane, 3-ethylpentane, 2,2,3-trimethylbutane, 2,2-dimethylpentane, cycloheptane, methylcyclohexane, 2,2-dimethylbutane and 2,3-dimethylbutane. Particularly preferred hydrocarbons are the C5 and C6 (cyclo)alkanes such as cyclopentane, n-pentane and isopentane, and any mixtures thereof and mixtures of any of these with isobutane.
A preferred blowing agent is a mixture of isopentane and n-pentane in a weight ratio of between 75:25 and 25:75, most preferably at a ratio 8/3. Another preferred blowing agent is a mixture of cyclopentane and isopentane and/or n-pentane in a weight ratio cyclopentane:n/isopentane of between 80:20 and 20:80, preferably 60:40 wherein the weight ratio npentane:isopentane is preferably between 0:100 and 50:50.
Suitable isocyanate-reactive compounds which may be employed in admixture with the TDA-initiated polyether polyols include any of those known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams. Of particular importance for the preparation of rigid foams are polyols and polyol mixtures having average hydroxyl numbers of from 300 to 1000, especially from 300 to 700 mg KOH/g, and hydroxyl functionalities of from 2 to 8, especially from 3 to 8. Suitable polyols have been fully described in the prior art and include reaction products of alkylene oxides, for example ethylene oxide and/or propylene oxide, with initiators containing from 2 to 8 active hydrogen atoms per molecule. Suitable initiators include: polyols, for example glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol and sucrose; polyamines, for example ethylene diamine, the various isomers of phenylene diamine, 4-chloro-o-phenylenediamine, 4-chloro-m-phenylenediamine, 4,5-dichloro-o-phenylenediamine, 4,5-dimethyl-o-phenylenediamine, 4-methoxy-o-phenylenediamine, 2-nitro-p-phenylenediamine, 4-4xe2x80x2-methylenebis(o-chloroaniline), 4,4xe2x80x2-methylenebis(3-nitroaniline), 3,3xe2x80x2-diaminobenzidine, 1,5-diaminonaphthalene, diaminodiphenylmethane, polymethylene polyphenylene polyamines; and aminoalcohols, for example ethanolamine and diethanolamine; and mixtures of such initiators. In a preferred embodiment of the present invention aliphatic amine initiated polyether polyols are not used, in particular when cyclopentane is used as blowing agent. Other suitable polymeric polyols include polyesters obtained by the condensation of appropriate proportions of glycols and higher functionality polyols with dicarboxylic or polycarboxylic acids. Still further suitable polymeric polyols include hydroxyl terminated polythioethers, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes.
In a preferred embodiment of the present invention the TDA-initiated polyether polyol is used together with other polyether polyols and up to 20 wt % (based on total polyols) of polyester polyols. The hydroxyl value of the polyol blend is generally between 350 and 550 mg KOH/g, more preferably between 380 and 430 mg KOH/g.
Preferably the TDA-initiated polyether polyol is used together with other aromatic amine initiated polyether polyols so that the total amount of aromatic amine initiated polyether polyols is between 40 and 100%, preferably between 50 and 90%, most preferably between 60 and 70% by weight based on total polyols. Preferred aromatic amine initiated polyether polyols to be used together with the TDA-initiated polyether polyol of the present invention are DADPM-initiated polyether polyols.
Preferred non aromatic amine initiated polyether polyols which can be used in the process of the present invention include sucrose and/or sorbitol-initiated polyether polyol.
Suitable organic polyisocyanates for use in the process of the present invention include any of those known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams, and in particular the aromatic polyisocyanates such as diphenylmethane diisocyanate in the form of its 2,4xe2x80x2-, 2,2xe2x80x2- and 4,4xe2x80x2-isomers and mixtures thereof, the mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof known in the art as xe2x80x9ccrudexe2x80x9d or polymeric MDI (polymethylene polyphenylene polyisocyanates) having an isocyanate functionality of greater than 2, toluene diisocyanate in the form of its 2,4- and 2,6-isomers and mixtures thereof, 1,5-naphthalene diisocyanate and 1,4-diisocyanatobenzene. Other organic polyisocyanates which may be mentioned include the aliphatic diisocyanates such as isophorone diisocyanate, 1,6-diisocyanatohexane and 4,4xe2x80x2-diisocyanatodicyclohexylmethane.
The quantities of the polyisocyanate compositions and the polyfunctional isocyanate-reactive compositions to be reacted will depend upon the nature of the rigid polyurethane or urethane-modified polyisocyanurate foam to be produced and will be readily determined by those skilled in the art.
In addition to the hydrocarbon blowing agent(s) other physical blowing agents may be used in amounts up to 20 mole % of the total physical blowing agents present.
Suitable other physical blowing agents include those well known and described in the art, for example dialkyl ethers, alkyl alkanoates, aliphatic and cycloaliphatic hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons and fluorine-containing ethers.
Generally water or other carbon dioxide-evolving compounds are used together with the physical blowing agents. Where water is used as chemical co-blowing agent typical amounts are in the range from 0.2 to 5%, preferably from 0.5 to 3% by weight based on the isocyanate-reactive compound.
The total quantity of blowing agent to be used in a reaction system for producing cellular polymeric materials will be readily determined by those skilled in the art, but will typically be from 2 to 25% by weight based on the total reaction system.
In order to reduce the cell sizes of the foam and accordingly to improve the thermal insulation properties an insoluble fluorinated compound may be used in the foam-forming process according to the present invention. Such insoluble fluorinated compounds include any of those disclosed in U.S. Pat. Nos. 4,981,879, 5,034,424, 4,792,002, EP 508649 and WO 95/18176. Certain of said insoluble fluorinated compounds suitable for use in the process of the invention may themselves act as blowing agents under the conditions pertaining to the foam-forming reaction, particularly where their boiling point is lower than the exotherm temperature achieved by the reaction mixture.
In addition to the polyisocyanate and polyfunctional isocyanate-reactive compositions and the blowing agent, the foam-forming reaction mixture will commonly contain one or more other auxiliaries or additives conventional to formulations for the production of rigid polyurethane and urethane-modified polyisocyanurate foams. Such optional additives include crosslinking agents, for examples low molecular weight polyols such as triethanolamine, foam-stabilising agents or surfactants, for example siloxane-oxyalkylene copolymers, urethane catalysts, for example tin compounds such as stannous octoate or dibutyltin dilaurate or tertiary amines such as dimethylcyclohexylamine or triethylene diamine, fire retardants, for example halogenated alkyl phosphates such as tris chloropropyl phosphate, and fillers such as carbon black.
In operating the process for making rigid foams according to the invention, the known one-shot, prepolymer or semi-prepolymer techniques may be used together with conventional mixing methods and the rigid foam may be produced in the form of slabstock, mouldings, cavity fillings, sprayed foam, frothed foam or laminates with other materials such as hardboard, plasterboard, plastics, paper or metal.
It is convenient in many applications to provide the components for polyurethane production in pre-blended formulations based on each of the primary polyisocyanate and isocyanate-reactive components. In particular, many reaction systems employ a polyisocyanate-reactive composition which contains the major additives such as the blowing agent and the catalyst in addition to the polyisocyanate-reactive component or components.
Therefore the present invention also provides a polyisocyanate-reactive composition comprising (a) hydrocarbon blowing agent(s) and a TDA-initiated polyether polyol in an amount of between 10 and 40% by weight based on total isocyanate-reactive compounds.
The various aspects of this invention are illustrated, but not limited by the following examples.
The following formulation and reaction components are referred to in the examples:
Polyol 1: a sorbitol initiated polyether polyol of OH value 460 mg KOH/g.
Polyol 2: a sorbitol initiated polyether polyol of OH value 420 mg KOH/g.
Polyol 3: a DADPM initiated polyether polyol of OH value 310 mg KOH/g.
Polyol 4: a TDA initiated polyether polyol of OH value 350 mg KOH/g.
Surfactant: a silicone surfactant.
Catalyst: a mixture of amine catalysts.
SUPRASEC DNR: a polymeric MDI available from Imperial Chemical Industries.
SUPRASEC is a trademark of Imperial Chemical Industries.


A molded structure comprises a decorative film or substrate, and an adjacent injection molded polymeric base comprising a substantially transparent cycloaliphatic polyester resin which may have an opening for exposing the transparent polymeric base resin to the exterior of the molded article, and a process for making the molded structure is described.

This invention relates to insert molded articles in which a substrate or film is back molded with an injection molded material.
In a typical in-mold decorating process, a printed substrate is formed into a three-dimensional shape and placed into a mold. Molten resin is then injected into the mold cavity space behind the formed substrate, forming a single molded part.
IMD may involve two types of film processes. According to one process, the film is a permanent fixture of the finished good. In this case, the film can act as the aesthetic effect carrier, and/or as a protective layer for the substrate resin, the ink, or both. Good adhesion is required between the film, such as a polycarbonate type film, and the substrate resin.
According to another process, the film may be a temporary carrier for the aesthetic effect. In this case the substrate resin is back-molded on the IMD film and the film is subsequently peeled off of the substrate resin, leaving the aesthetic material/design behind on the substrate resin. Good adhesion is not desired between the film, which may be a poly(ethylene terephthalate) type film and the substrate resin.
For both in-mold decorating (IMD) applications, ink washout of the IMD film is an inherent problem. In IMD applications, an ink (or other aesthetic enhancement) bearing or containing film is back-molded by a substrate resin for structural support. During the back-molding of the substrate material, the aesthetic ink or effect material is often sandwiched between the IMD film and the substrate resin. The resulting shear from the back-molding injection of the substrate resin material against the IMD film, coupled with the heat of the molten substrate resin can often cause the ink (or aesthetic bearing material) to detach itself from the IMD film. This results in an area of decreased ink concentration, or xe2x80x9cwashout.xe2x80x9d This washout is caused by several processing factors of the substrate resin, including processing temperature and injection shear.
Other challenges during the IMD process are foil breakage/wrinkling, again as a result of the high pressures and temperatures needed to back mold.
A resin used as an IMD substrate is a blend of polycarbonate (PC) with ABS (acrylonitrile-butadiene-styrene), such as Cycoloy produced by GE Plastics. One of the reasons is the superior shear thinning behavior of PC/ABS blends, which enables the molder to fill the mold at lower injection rates and temperatures.
U.S. Pat. No. 3,654,062 to Loew describes a molded decorative plaque having a laminated facing sheet which has the configuration of the mold. Heated plastic is injection molded behind the sheet to form the plaque. U.S. Pat. No. 6,117,384 to Laurin et al. describes a process where colors are decorated into a single film which is then incorporated with a molten resin injected behind the film to produce a permanently bonded three-dimensional piece. U.S. Pat. No. 4,391,954 to Scott describes a thermoplastic molding composition comprising an aromatic carbonate polymer and a polyester derived from a cyclohexanedimethanol. U.S. Pat. No. 4,125,572 to Scott describes a thermoplastic molding composition comprising an aromatic carbonate polymer and a polyester derived from an aliphatic or cycloaliphatic diol. U.S. Pat. No. 4,662,966 to Nissha Printing Co. Ltd. describes a transfer printing machine where designs of a diffusible dye on a transfer sheet is transferred to heated articles.
It is desired to have a material which has improved chemical resistance and can obtain low temperature impact with special effects and high clarity. The chemical resistance of many transparent, amorphous materials is not sufficient towards chemicals like oleic acid and/or coppertone, which are considered to be important chemicals in qualifying new materials in the telecom/electronics business. In some cases it is preferred to have a translucent material, since some light scattering can contribute to the desired effect.
A molded structure that comprises a decorative film or substrate, and an adjacent injection molded polymeric base comprising a substantially transparent cycloaliphatic polyester resin. In one embodiment, the substrate has at least one opening which exposes the transparent polymeric base resin to the exterior of the molded article.
According to a molding method, a printed substrate is formed into a three-dimensional shape and placed into a mold. Molten resin is then injected into the mold cavity space behind the formed substrate, forming a single molded part.
The use of a transparent cycloaliphatic polyester resin as the injection molded base material obviates disadvantages encountered with non-transparent PC/ABS type blends. Lack of transparency may be a significant drawback in certain applications. For instance, for some cell phones, a film (PET) with ink patterns is back molded with a transparent resin to mold the complete front cover. This is done so that information can be visually accessed by the product""s user through a transparent window which is integrated into the structural resin of the product""s design. During the back molding, ink may be transferred from the film to the transparent resin and then removed, resulting in a decorated front cover. An example of transfer printing the Nissha process. See U.S. Pat. No. 4,662,966 to Sumi et al.
For some applications, the film of substrate material may be a permanent aesthetic part of the finished product. For some wireless personal electronic applications which may use a film such as a polycarbonate (PC) film with ink patterns which is back molded with a transparent resin to mold the complete product housing. The transparent base material is molded to create a transparent window. Data may be transferred to/from the electronic product to its server by IR through the transparent window which is integrated into the structural resin of the product. Holes in the film expose the transparent injected molded base resin for either data transfer or aesthetic purposes.
One possibility for a transparent material is polycarbonate (PC). Typically, the processing temperature and injection shear (viscosity) of PC results in washout of ink on the IMD film at the injection gate. Other higher flow transparent materials (like LEXAN SP, a super high flow PC grade produced by GE Plastics) give an improvement in terms of viscosity, but have a very small processing window and as such are not very robust. Even these higher flow materials are not suitable for thinner-walled IMD parts where their fast injection speeds will still result in IMD washout and other issues as described above (e.g. foil breakage). In addition, physical properties (especially impact) of LEXAN SP and other such high-flow products are also not sufficient for use in many IMD applications.
Cycloaliphatic polyester/Polycarbonate blends and/or cycloaliphatic polyester/Polycarbonate/impact modified blends are utilized as a back-molded resin for in-mold decorated (IMD) film applications. Transparent blends of Polycarbonate (PC) and poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD) possess lower processing temperatures and improved flow characteristics over standard PC materials. This results in slower injection speeds and lower injection shear in an injection molded IMD part when compared to other transparent back-molding substrate resins (such as LEXAN SP) for in-mold decorating (IMD) applications. This in turn results in a decrease of the washout effect in IMD applications. These blends also offer superior chemical resistance and ductility to that of most transparent resin materials. The complete miscibility of this system allows the properties of the resulting blend to be dialed in, via blend ratio, while still maintaining transparency.
Two types of cycloaliphatic polyesters may desirable can be used with BPA-based polycarbonate to give the compositions and articles of this invention. The most preferred polyester molecules are derived from cycloaliphatic diol and cycloaliphatic diacid compounds, specifically polycyclohexane dimethanol cyclohexyl dicarboxylate (PCCD). The polyester having only one cyclic unit may also be useful.
In addition, PCCD and PC can be blended with certain impact modifiers (IM) at such ratios as to match the refractive index (RI) of the impact modifier to that of the PC/PCCD blend and therefore still retain transparency. In addition to the characteristics of PC/PCCD resins, these PC/PCCD/IM blends possess improved low temperature ductility which can be a key requirements for IMD applications, for example, cellphone covers.
The present invention is directed to multi-layer plastic articles and methods for making such articles. More particularly, the articles comprise a base layer of an injection molded thermoplastic and surface layer of a decorated film. The multi-layer film comprises a fluoride polymer layer laminated to a polycarbonate layer.
A method for producing multi-layered films with the properties of: formable, low birefringence, chemical, and UV radiation resistance, and optical transparency is set forth. These laminated films are well suited for exterior automotive insert mold decoration (IMD) applications. IMD is the process by which the formed, and decorated film is placed in the mold and the thermoplastic melt, which forms the base layer, is injection molded to the exposed surface of the film
According to one embodiment, molded articles are prepared by the steps of:
(1) providing a decorative substrate, such as polycarbonate, having one or more colors on a surface, for example by screen printing;
(2) forming and trimming the printed substrate into a three-dimensional shape;
(5) fitting the printed substrate into a mold having a surface which matches the three-dimensional shape of the substrate; and
(6) injecting a substantially transparent resin comprising a blend of cycloaliphatic polyester resin and a polycarbonate resin, into the mold cavity behind the printed substrate to produce a one-piece, permanently bonded three-dimensional product.
The injection molded substantially transparent resin comprises a transparent cycloaliphatic polyester resin and more preferably a cycloaliphatic polyester resin blended with polycarbonate.
In cases where the polycarbonate has a high Tg and is difficult to process the cycloaliphatic polyester acts to lower the PC Tg. A blend with a cycloaliphatic polyester reduces Tg making melt processing easier while the blend has excellent optical properties overall. The most preferred materials will be blends where the polyester has both cycloaliphatic diacid and cycloaliphatic diol components specifically polycyclohexane dimethanol cyclohexyl dicarboxylate (PCCD). The preferred polycarbonate will be composed of units of BPA, SBI bis phenol, aryl substituted bisphenols, cycloaliphatic bisphenols and mixtures thereof. It is contemplated that acidic phosphorus based stabilizers are useful to retard melt reaction of the cycloaliphatic polyester and polycarbonate resin and improve color.
The ratio of cycloaliphatic polyester to polycarbonate in the range of 40:60 to 5:95% by weight of the entire mixture is preferred. Blends from 50:50 to 30:70 are most preferred.
The cycloaliphatic polyester resin comprises a polyester having repeating units of the formula I:
where at least one R or R1 is a cycloalkyl containing radical.
The polyester is a condensation product where R is the residue of an aryl, alkane or cycloalkane containing diol having 6 to 20 carbon atoms or chemical equivalent thereof, and R1 is the decarboxylated residue derived from an aryl, aliphatic or cycloalkane containing diacid of 6 to 20 carbon atoms or chemical equivalent thereof with the proviso that at least one R or R1 is cycloaliphatic. Preferred polyesters of the invention will have both R and R1 cycloaliphatic.
The present cycloaliphatic polyesters are condensation products of aliphatic diacids, or chemical equivalents and aliphatic diols, or chemical equivalents. The present cycloaliphatic polyesters may be formed from mixtures of aliphatic diacids and aliphatic diols but must contain at least 50 mole % of cyclic diacid and/or cyclic diol components, the remainder, if any, being linear aliphatic diacids and/or diols. The cyclic components are necessary to impart good rigidity to the polyester and to allow the formation of transparent blends due to favorable interaction with the polycarbonate resin.
The polyester resins are typically obtained through the condensation or ester interchange polymerization of the diol or diol equivalent component with the diacid or diacid chemical equivalent component.
R and R1 are preferably cycloalkyl radicals independently selected from the following formula:
The preferred cycloaliphatic radical R1 is derived from the 1,4-cyclohexyl diacids and most preferably greater than 70 mole % thereof in the form of the trans isomer. The preferred cycloaliphatic radical R is derived from the 1,4-cyclohexyl primary diols such as 1,4-cyclohexyl dimethanol, most preferably more than 70 mole % thereof in the form of the trans isomer.
Other diols useful in the preparation of the polyester resins of the present invention are straight chain, branched, or cycloaliphatic alkane diols and may contain from 2 to 16 carbon atoms. Examples of such diols include but are not limited to ethylene glycol; propylene glycol, i.e., 1,2- and 1,3-propylene glycol; 2,2-dimethyl-1,3-propane diol; 2-ethyl, 2-methyl, 1,3-propane diol; 1,3- and 1,5-pentane diol; dipropylene glycol; 2-methyl-1 ,5-pentane diol; 1,6-hexane diol; dimethanol decalin, dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and particularly its cis- and trans-isomers; 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCBD), triethylene glycol; 1,10-decane diol; and mixtures of any of the foregoing. Preferably a cycloaliphatic diol or chemical equivalent thereof and particularly 1,4-cyclohexane dimethanol or its chemical equivalents are used as the diol component.
Chemical equivalents to the diols include esters, such as dialkylesters, diaryl esters and the like.
The diacids useful in the preparation of the aliphatic polyester resins of the present invention preferably are cycloaliphatic diacids. This is meant to include carboxylic acids having two carboxyl groups each of which is attached to a saturated carbon. Preferred diacids are cyclo or bicyclo aliphatic acids, for example, decahydro naphthalene dicarboxylic acids, norbornene dicarboxylic acids, bicyclo octane dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid or chemical equivalents, and most preferred is trans-1,4-cyclohexanedicarboxylic acid or chemical equivalent. Linear dicarboxylic acids like adipic acid, azelaic acid, dicarboxyl dodecanoic acid and succinic acid may also be useful.
Cyclohexane dicarboxylic acids and their chemical equivalents can be prepared, for example, by the hydrogenation of cycloaromatic diacids and corresponding derivatives such as isophthalic acid, terephthalic acid or naphthalenic acid in a suitable solvent such as water or acetic acid using a suitable catalysts such as rhodium supported on a carrier such as carbon or alumina. See, Friefelder et al., Journal of Organic Chemistry, 31, 3438 (1966); U.S. Pat. Nos. 2,675,390 and 4,754,064. They may also be prepared by the use of an inert liquid medium in which a phthalic acid is at least partially soluble under reaction conditions and with a catalyst of palladium or ruthenium on carbon or silica. See U.S. Pat. Nos. 2,888,484 and 3,444,237.
Typically, in the hydrogenation, two isomers are obtained in which the carboxylic acid groups are in cis- or trans-positions. The cis- and trans-isomers can be separated by crystallization with or without a solvent, for example, n-heptane, or by distillation. The cis-isomer tends to blend better; however, the trans-isomer has higher melting and crystallization temperatures and may be preferred. Mixtures of the cis- and trans-isomers are useful herein as well.
When the mixture of isomers or more than one diacid or diol is used, a copolyester or a mixture of two polyesters may be used as the present cycloaliphatic polyester resin.
Chemical equivalents of these diacids include esters, alkyl esters, e.g., dialkyl esters, diaryl esters, anhydrides, salts, acid chlorides, acid bromides, and the like. The preferred chemical equivalents comprise the dialkyl esters of the cycloaliphatic diacids, and the most favored chemical equivalent comprises the dimethyl ester of the acid, particularly dimethyl-1,4-cyclohexane-dicarboxylate.
A preferred cycloaliphatic polyester is poly(cyclohexane-1,4-dimethylene cyclohexane-1,4-dicarboxylate) also referred to as poly(1,4-cyclohexane-dimethanol-1,4-dicarboxylate) (PCCD) which has recurring units of formula II:
With reference to the previously set forth general formula, for PCCD, R is derived from 1,4 cyclohexane dimethanol; and R1 is a cyclohexane ring derived from cyclohexanedicarboxylate or a chemical equivalent thereof. The favored PCCD has a cis/trans formula.
The polyester polymerization reaction is generally run in the melt in the presence of a suitable catalyst such as a tetrakis(2-ethyl hexyl)titanate, in a suitable amount, typically about 50 to 200 ppm of titanium based upon the final product.
The preferred aliphatic polyesters used in the present transparent molding compositions have a glass transition temperature (Tg) which is above 50xc2x0 C., more preferably above 80xc2x0 C. and most preferably above about 100oC.
Also contemplated herein are the above polyesters with from about 1 to about 50 percent by weight, of units derived from polymeric aliphatic acids and/or polymeric aliphatic polyols to form copolyesters. The aliphatic polyols include glycols, such as poly(ethylene glycol) or poly(butylene glycol). Such polyesters can be made following the teachings of, for example, U.S. Pat. Nos. 2,465,319 and 3,047,539.
Polycarbonates useful in the invention comprise the divalent residue of dihydric phenols, Ar xe2x80x2, bonded through a carbonate linkage and are preferably represented by the general formula III:
wherein A is a divalent hydrocarbon radical containing from 1 to about 15 carbon atoms or a substituted divalent hydrocarbon radical containing from 1 to about 15 carbon atoms; each X is independently selected from the group consisting of hydrogen, halogen, and a monovalent hydrocarbon radical such as an alkyl group of from 1 to about 8 carbon atoms, an aryl group of from 6 to about 18 carbon atoms, an arylalkyl group of from 7 to about 14 carbon atoms, an alkoxy group of from 1 to about 8 carbon atoms; and m is 0 or 1 and n is an integer of from 0 to about 5. Arxe2x80x2 may be a single aromatic ring like hydroquinone or resorcinol, or a multiple aromatic ring like biphenol or bisphenol A.
The dihydric phenols employed are known, and the reactive groups are thought to be the phenolic hydroxyl groups. Typical of some of the dihydric phenols employed are bis-phenols such as bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol-A), 2,2-bis(4-hydroxy-3,5-dibromo-phenyl)propane; dihydric phenol ethers such as bis(4-hydroxyphenyl)ether, bis(3,5-dichloro-4-hydroxyphenyl)ether; p,pxe2x80x2-dihydroxydiphenyl and 3,3xe2x80x2-dichloro4,4xe2x80x2-dihydroxydiphenyl; dihydroxyaryl sulfones such as bis(4-hydroxyphenyl)sulfone, bis(3,5-dimethyl4-hydroxyphenyl)sulfone, dihydroxy benzenes such as resorcinol, hydroquinone, halo- and alkyl-substituted dihydroxybenzenes such as 1,4-dihydroxy-2,5-dichlorobenzene, 1,4-dihydroxy-3-methylbenzene; and dihydroxydiphenyl sulfides and sulfoxides such as bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfoxide and bis(3,5-dibromo4-hydroxyphenyl)sulfoxide. A variety of additional dihydric phenols are available and are disclosed in U.S. Pat. Nos. 2,999,835, 3,028,365 and 3,153,008; all of which are incorporated herein by reference. It is, of course, possible to employ two or more different dihydric phenols or a combination of a dihydric phenol with a glycol.
The carbonate precursors are typically a carbonyl halide, a diarylcarbonate, or a bishaloformate. The carbonyl halides include, for example, carbonyl bromide, carbonyl chloride, and mixtures thereof. The bishaloformates include the bishaloformates of dihydric phenols such as bischloroformates of 2,2-bis(4-hydroxyphenyl)-propane, hydroquinone, and the like, or bishaloformates of glycol, and the like. While all of the above carbonate precursors are useful, carbonyl chloride, also known as phosgene, and diphenyl carbonate are preferred.
The aromatic polycarbonates can be manufactured by any processes such as by reacting a dihydric phenol with a carbonate precursor, such as phosgene, a haloformate or carbonate ester in melt or solution. U.S. Pat. No. 4,123,436 describes reaction with phosgene and U.S. Pat. No. 3,153,008 describes a transesterification process.
Preferred polycarbonate will be made of dihydric phenols that result in resins having low birefringence for example dihydric phenols having pendant aryl or cup shaped aryl groups like:
Phenyl-di(4-hydroxyphenyl)ethane(acetophenone bisphenol):
Diphenyl-di(4-hydroxyphenyl)methane(benzophenone bisphenol):
2,2-bis(3-phenyl4-hydroxyphenyl)propane
2,2-bis-(3,5-diphenyl-4-hydroxyphenyl)propane;
bis-(2-phenyl-3-methyl4-hydroxyphenyl)propane;
2,2xe2x80x2-bis(hydroxyphenyl)fluorene;
1,1-bis(5-phenyl4-hydroxyphenyl)cyclohexane;
3,3xe2x80x2-diphenyl4,4xe2x80x2-dihydroxy diphenyl ether;
2,2-bis(4-hydroxyphenyl)-4,4-diphenyl butane;
1,1-bis(4-hydroxyphenyl)-2-phenyl ethane;
2,2-bis(3-methyl-4-hydroxyphenyl)-1-phenyl propane;
6,6xe2x80x2-dihdyroxy-3,3,3xe2x80x2,3xe2x80x2-tetramethyl-1,1xe2x80x2-spiro(bis)indane;
(hereinafter xe2x80x9cSBIxe2x80x9d), or dihydric phenols derived from Spiro biindane of formula IV:
Units derived from SBI and its 5-methyl homologue are preferred, with SBI being most preferred.
Other dihydric phenols which are typically used in the preparation of the polycarbonates are disclosed in U.S. Pat. Nos. 2,999,835, 3,038,365, 3,334,154 and 4,131,575. Branched polycarbonates are also useful, such as those described in U.S. Pat. Nos. 3,635,895 and 4,001,184. Polycarbonate blends include blends of linear polycarbonate and branched polycarbonate.
It is also possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with an aliphatic dicarboxylic acids like; dimer acids, dodecane dicarboxylic acid, adipic acid, azelaic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired for use in the preparation of the polycarbonate mixtures of the invention. Most preferred are aliphatic C5 to C12 diacid copolymers.
The preferred polycarbonates are preferably high molecular weight aromatic carbonate polymers have an intrinsic viscosity (as measured in methylene chloride at 25xc2x0 C.) ranging from about 0.30 to about 1.00 dl/gm. Polycarbonates may be branched or unbranched and generally will have a weight average molecular weight of from about 10,000 to about 200,000, preferably from about 20,000 to about 100,000 as measured by gel permeation chromatography. It is contemplated that the polycarbonate may have various known end groups.
In the thermoplastic compositions which contain a cycloaliphatic polyester resin and a polycarbonate resin it is preferable to use a stabilizer or quencher material. Catalyst quenchers are agents which inhibit activity of any catalysts which may be present in the resins. Catalyst quenchers are described in detail in U.S. Pat. No. 5,441,997. It is desirable to select the correct quencher to avoid color formation and loss of clarity to the polyester polycarbonate blend.
A preferred class of stabilizers including quenchers are those which provide a transparent and colorless product. Typically, such stabilizers are used at a level of 0.001-10 weight percent and preferably at a level of from 0.005-2 weight percent. The favored stabilizers include an effective amount of an acidic phosphate salt; an acid, alkyl, aryl or mixed phosphite having at least one acidic hydrogen; a Group IB or Group IIB metal phosphate salt; a phosphorus oxo acid, a metal acid pyrophosphate or a mixture thereof. The suitability of a particular compound for use as a stabilizer and the determination of how much is to be used as a stabilizer may be readily determined by preparing a mixture of the polyester resin component and the polycarbonate and determining the effect on melt viscosity, gas generation or color stability or the formation of interpolymer. The acidic phosphate salts include sodium dihydrogen phosphate, mono zinc phosphate, potassium hydrogen phosphate, calcium dihydrogen phosphate and the like. The phosphites may be of the formula V:
where R1, R2 and R3 are independently selected from the group consisting of hydrogen, alkyl and aryl with the proviso that at least one of R1, R2 and R3 is hydrogen.
The phosphate salts of a Group IB or Group IIB metal include zinc phosphate and the like. The phosphorus oxo acids include phosphorous acid, phosphoric acid, polyphosphoric acid or hypophosphorous acid.
The polyacid pyrophosphates may be of the formula VI:
MzxHyPnO3n+1
wherein M is a metal; x is a number ranging from 1 to 12 and y is a number ranging 1 to 12, n is a number from 2 to 10, z is a number from 1 to 5 and the sum of (xz)+y is equal to n+2. The preferred M is an alkaline or alkaline earth metal.
The most preferred quenchers are oxo acids of phosphorus or acidic organo phosphorus compounds. Inorganic acidic phosphorus compounds may also be used as quenchers, however they may result in haze or loss of clarity. Most preferred quenchers are phosphoric acid, phosphorous acid or their partial esters.
Mold releases such as pentaerythritol tetra esters, especially the stearate esters. Also preferred are carboxylic acid esters of other polyols like glycerol; for example glycerol mono stearate.
In one embodiment, the polycabonate/cycloaliphatic polyester compositions may include less than about 20 percent, and preferably less than about 15 percent of an impact modifier. Typical impact modifiers generally comprise an acrylic or methacrylic grafted polymer of a conjugated diene or an acrylate elastomer, alone, or copolymerized with a vinyl aromatic compound. En general these impact modifiers contain units derived from butadiene or isoprene, alone or in combination with a vinyl aromatic compound, or butyl acrylate, alone or in combination with a vinyl aromatic compound. Other typical impact modifiers include, but are not limited to ethylene vinyl acetate, ethylene ethylacrylate copolymers, SEBS (styrene-ethylene-butylene styrene) and SBS (styrene-butadiene-strene)block copolymers, EPDM (ethylene propyleue diene monomer) and EPR (ethylene propylene rubber)copolymers, etc
According to a preferred embodiment, transparent and highly ductile compositions can be obtained via the blending of poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD), PC and a transparent impact modifier with a refractive index (RI) between 1.51 and 1.58. The complete miscibility of PC and PCCD allows adjustment of the RI of the PC/PCCD blend to the RI of the impact modifier. There are many impact modifiers which are suitable and some examples are given to illustrate. Examples of such impact modifiers are a clear ABS (acrylonitrile-butadiene-styrene, RI=1.535) and typical PVC modifiers like Blendex 415/336 (ABS material) supplied by GE Plastics or Paraloid ETA 702/736 (MBS material) supplied by Rohm and Haas or Kane Ace B28/B58 (S material) supplied by Kaneka. All these PVC modifiers do have a RI between 1.53 and 1.55. These parts have a unique combination of impact, transparency and chemical resistance.
Additionally, additives such as mold releases, antioxidants lubricants, nucleating agents such as talc and the like, other stabilizers including but not limited to UV stabilizers, such as benzotriazole, supplemental reinforcing fillers, and the like, flame retardants, pigments or combinations thereof may be added to the compositions of the present invention.
Adding visual effect additives like metal or mica flakes in combination with organic dyes does not result in a significant increase of the temperature where the material becomes brittle.
The multi-layer films of this invention can be transparent, or opaque as desired. Transparent products are preferred embodiments of this invention. The fluoride polymer and polycarbonate layers are first laminated together. A variety of laminating techniques can be used. However, heat lamination is preferred. Acrylic adhesives are preferred for use in the present invention.
A preferred substrate or film is one formed from a thermoplastic polycarbonate material such as previously described. Typical examples of polycarbonate resins are described in U.S. Pat. No. 4,351,920, which is incorporated herein by reference, and are obtained by the reaction of aromatic dihydroxy compounds with phosgene. A preferred aromatic dihydroxy compound is 2,2-bis(4-hydroxy phenyl)propane, (i.e., Bisphenol-A). The term aromatic polycarbonate resins is also meant to include polyester carbonates obtained from the reaction products of a dihydroxy phenol, a carbonate precursor and a dicarboxylic acid such as terephthalic acid and isophthalic acid. Optionally an amount of a glycol may also be used as a reactant. A preferred grade of polycarbonate resin for the film is LEXAN grade ML9103 available from General Electric Company. Polycarbonate film may be made by well-known methods. Typically, the molten thermoplastic is cast onto an extrusion roll stack, and both sides of the material are polished and pressed to a uniform thickness. Preferably the polycarbonate film has a thickness of from five (5) to twenty (20) mils.
It is contemplated that the film or substrate may have multiple layers which includes an outer weather resistant layer. An example of such a film or substrate are layers of a polycarbonate film layer or other transparent substrate; optionally, a layer of polyvinylidene fluoride (xe2x80x9cPVDFxe2x80x9d) film or other material resistant to ultraviolet (UV) light laminated to the polycarbonate film; and a decorated layer, which may be varied as desired, and which is printed on the exposed surface of the polycarbonate layer.
One of the most efficient and cost-effective ways of decorating a part is to do it during the molding cycle. One way to accomplish this is by inserting a decorated substrate into the cavity of a molding tool and injecting plastic behind it. This process is generally known as in-mold decoration or insert mold decoration (IMD). The decoration for the finished part can either be exposed to the environment (xe2x80x9cfirst surface decorationxe2x80x9d) and/or encapsulated between the substrate and the injected material (xe2x80x9csecond surface decorationxe2x80x9d).
Other parameters contribute to the preparation of the second surface decorated parts. First, high temperature, formable inks are preferably used for the graphics. Second surface decoration requires more robust ink systems to provide adequate ink adhesion during the molding process. Moreover, in applications such as light assemblies where light transmission is critical, dye inks should be used rather than pigmented inks so as not to affect light transmission and haze readings. Evaluation of many different inks indicates that many ink systems are not suitable for second surface decorating. Among those inks which are appropriate are the following: Naz-dar 9600, Colonial/Coates C-37 Series, Marabuwerke IMD Spezialfarbe 3060, Nor-cote (UK) IMD Series.
Prototype molds may be constructed from common materials such as plaster, hard woods, fiberglass, syntactic foam and silicone. These materials are relatively easy to work with and allow minor modifications. It is common practice for designers to experiment with IMD to cast a silicone forming mold off an existing injection mold. For example, production forming tools should be constructed of durable materials such as cast or machined aluminum, steel or metal filled epoxy. Conductive molds should be internally heated to a temperature of 250xc2x0 F.
The formed part will contract in size once it is removed from the mold and allowed to cool. The amount of shrinkage depends on the material selected, but it is predictable and must be accounted for when calculating the mold dimensions. The same is true for the expansion of the mold at operating temperatures. For example, LEXAN(copyright) polycarbonate film will typically shrink approximately 0.5-0.9% after forming, depending on the mold. The thermal expansion properties of the mold material at an operating temperature of 250xc2x0 F. must be subtracted from the film shrinkage number to obtain accurate mold dimensions. In addition, draft angles of 5 to 7 degrees are suggested to facilitate part removal from male molds. Female molds require less draft (1 to 2 degrees).
The basic considerations in gating are part design, flow, end use requirements and location of in-mold graphics. The standard guidelines of traditional gating apply to IMD along with several extra considerations. For example, one gate should be used whenever possible to minimize the potential for wrinkling the film. Gates should be located away from end-use impact as well as to provide flow from thick to thin sections to minimize weld lines. Gates should also be located at right angles to the runner to minimize jetting, splay and gate blush. Large parts requiring multiple gates should include gate positions close enough together to reduce pressure loss. Sequential gating may be used to prevent folding of the film at weld lines. Gate land lengths should be kept as short as possible. An impinging gate may be used to ensure that the incoming flow is directed against the cavity wall or core to prevent jetting. Venting (particularly full perimeter venting) may be accomplished by knock outs, cores and parting lines and should be used whenever possible to avoid trapped gas that can burn and rupture the film. In addition, flow restrictions near gate areas can increase the potential for wash out due to increased shear. If bosses, core shutoffs, etc., are needed near a gate, rounded features or corners should be used to reduce shear. Finally, care should also be taken to ensure that the gating distributes the injection pressure over a large area, thus reducing the shear forces at the gate. Examples of gates that accomplish this include fan gates and submarine gates that enter the part via a rib.
When selecting a resin, it is advantageous that the resin""s viscosity be sufficiently low such that the pressure necessary to inject it into the mold may be reduced. In addition, the injection may be profiled so that the viscosity of the injected material maintained at a sufficiently low level in the gate area and may be raised after a suitable skin layer is established near the gate. At lower viscosity, the shear force of the injected material is lower and is therefore less likely to disturb the ink on the second surface of the substrate.
It is also possible to print the graphics on the substrate so that they extend beyond the gating area and into the runner system. In this case, if the ink is disturbed by the flow of the injected material, it will be disturbed in the runner area that will be trimmed off after the part is ejected from the mold.
Of course, runnerless systems or heated gating systems may also be employed. With a runnerless system, the drop diameter must be large enough to sufficiently distribute the pressure or flow into a part, such as a rib, which does. With a heated gating system, the tips of the heated gates be maintained at a temperature sufficiently below the softening temperature of the substrate so as to prevent substrate deformation.
Screen-printing is an example of a suitable technique for producing graphics on the film substrates of the present invention. Screen-printing is essentially a stencil printing process which may now be generated by computer with the aid of various software packages. Its ability to vary and control ink thickness accurately has made it an extremely useful process for the decoration of many different types of plastic substrates.
In screenprinting, a screen or stencil is prepared and bonded to a fine weave fabric which is then tensioned in a rigid frame. Frames may be made of either wood or metal, with metal being preferred. The frame must be dimensionally stable and able to withstand handling during the printing process. Screen fabrics are generally made from metallized polyester, nylon, stainless steel, and most commonly, polyester. The fabric is tightly woven under precise control using dimensionally exact filaments. There are a number of variables that affect ink deposit, including thread diameter, squeegee angle and hardness, emulsion thickness, etc. Higher mesh screens are suggested for formed IMD applications.
The basic screenprinting process involves the use of a flat bed where the substrate is held by vacuum during printing. A frame holder positions the screen and holds it both vertically and horizontally during the printing process. With the screen lowered over the substrate bed and held at the off contact distance by the press, the squeegee carrier moves the blade across the screen at a preset speed, pressure, stroke and angle.
It is important to register artwork during a screenprinting operation. This is normally done by locking the frame into a holder that aligns the frame using pins or holders. The pin alignment method is generally preferred because the artwork can be aligned along with the screen frame. Alignment of the substrate with the print image is done through the use of edge guides, mechanical stops or automatic devices. The first color is aligned by this method and subsequent colors are aligned through the use of targets or gauge marks which are printed along side the artwork.
Once the ink is printed, it must be either dried or cured depending on the ink technology used. If the ink is solvent or water based, then a gas fired or electric dryer can be used to dry the ink. When printing on plastic films, it is important to control the temperature and dwell time in the oven to avoid distorting the film. If a solvent ink is used, it is important to use an oven with good air flow to dissipate the fumes. It is also possible to use an infrared dryer on some ink types, but particular attention must be paid to the temperature control of the system. If the ink is UV curable, many suitable commercial units are available for curing such reactive ink types.
If the final piece is three dimensional, there are two basic techniques for forming 3D IMD parts. For parts having a draw depth greater than {fraction (1/2)} inch, thermoforming is suggested. For parts containing detailed alphanumeric graphics or draw depths less than xc2xd inch, cold forming is preferred.


A substantially flexible, dry matrix, which contains not more than about 3% moisture at room temperature, is impregnated with a water free treatment mixture containing a lipid and a surfactant. In a preferred embodiment, the mixture includes a glycol, a surfactant and a lipid emollient, lubricant, medicament or skin protectant. Methods of manufacturing and using the impregnated matrices are also taught.

1. Field of the Invention
The present invention relates to a treated matrix and method for making and using the same. More particularly, the present invention relates to a matrix treated with at least one lipid, emollients, lubricants, antimicrobial agents, skin protectants or medicaments and a surfactant. This matrix transfers the lipid to a skin surface as a thin film on contact.
2. Description of the Art
Heretofore, emollients, protectants, medicaments and lubricants that are slightly, or not, soluble in water have been applied using emulsions oil and water. Examples of such emulsions include skin lotions and other skin care products. However, such emulsions are non-uniform, separate, and are susceptible to bacterial growth. While the addition of surfactants improves and extends the life of emulsion, such additions do not solve the problems since oil and water simply do not mix. Moreover, such compositions are difficult to formulate and apply.
U.S. Pat. No. 5,091,102, entitled Method of Making a Dry Antimicrobial Fabric, issued to Sheridan, the applicant herein, on Feb. 25, 1992, and was assigned to the same assignee as the present application. This patent is directed to a method of making a substantially flexible dry matrix or towel for use in cleaning a surface by removing dust and/or organic film products. The Sheridan U.S. Pat. No. 5,091,102 matrix includes a glycol compound, a cationic surfactant, and antimicrobial agent and, in a preferred form, a nonionic surfactant, each of which is water soluble
As disclosed in Sheridan U.S. Pat. No. 5,091,102, in example 1 thereof, at col. 9 line 40-col. 10 line 23, commercially available dust cloths cannot clean a surface because they are incompatible with water and leave an oil-in-water smear behind. Even hen squeezed dry, they are oily and create more dirt to be cleaned. The invention described in Sheridan U.S. Pat. No. 5,091,102 solved the problem by being able to clean with water. Because the components are water soluble, they are able to clean the surface with water. Sheridan""s, success was attributable to restricting the cleaning components to water soluble materials.
Sheridan U.S. Pat. No. 5,091,102, however, did not address the specific problem confronted herein, namely providing a vehicle or matrix for transferring an emollient, lubricant, protectant, and/or medicament where at least one of the components was water insoluble as defined in the CRC Handbook of Chemistry and Physics. i.e., an emollient, petrolatum, zinc oxide, vitamin A, vitamin D, zinc carbonate, etc., or of low water solubility, i.e., slightly soluble1 in water such as zinc citrate, zinc phenate, sulfadiazole, sulfa-guanidine, citronellol, hydantoin, etc. As used herein, the terms soluble and slightly soluble are used in the conventional sense (see Hackh""s Chemical Dictionary, for example). This is particularly applicable to transferring a skin care product to the skin from the matrix.
1 Slightly solublexe2x80x94soluble in water on a relative scale: 1=insoluble, 2=slightly insoluble, 3=soluble, 4=very soluble. 5=miscible (CRC Handbook of Chemistry and Physics, 75th Edition, David R. Gide, page 1-3). Solublexe2x80x94capable of mixing with a liquid (dissolving) to form a homogeneous solution. The degree of solubility may conventionally be expressed: very solublexe2x80x94less than 1 part solvent freely solublexe2x80x94from 1 to 10 parts solvent solublexe2x80x94from 10 to 30 parts solvent sparingly solublexe2x80x94from 30 to 100 parts solvent slightly solublexe2x80x94from 100 to 1000 parts solvent very slightly solublexe2x80x94from 1000 to 10,000 parts solvent insolublexe2x80x94more than 10,000 parts solvent needed to dissolve 1 part substance (solute). (Hackh""s Chemical Dictionary, 3d Edition, p.787.)
Against the foregoing background, it is a primary object of the present invention to provide a dry matrix which is impregnated with a mixture of at least one liquid surfactant and a lipid such as an emollient, a lubricant, a medicament and/or a skin protectant2.
2 xe2x80x9c[L]ipids are material which are soluble in organic solvents and essentially insoluble in water.xe2x80x9d R. M. Burton and F. C. Guerra. FUNDAMENTALS OF LIPID CHEMISTRY, 2 (1974).
It is another object of the present invention to provide a method of making the impregnated matrix of the present invention.
It is a further object of the present invention to provide a substantially water-free treated matrix for shipping.
It is yet a further object of the present invention to provide a treated matrix that does not require packaging effective to prevent the evaporation of water or solvents.
It is yet another object of the present invention to provide a treated matrix that is microbially stable, even when not packaged within a moisture migration barrier.
It is a still further object of the present invention to provide such a matrix which, when exposed to water and pressure, will substantially instantaneously form an emulsion which can serve to transfer the surfactant, the emollient, lubricant, medicament and/or protectant from the matrix to a skin surface.
To accomplish these and other objects of the present invention, the composition of the present invention comprises a substantially flexible, dry matrix having a moisture content not exceeding about 3%, impregnated with a water-free treatment mixture. The matrix is adapted to transfer lipid components in said treatment mixture to a skin surface on contact. The treatment mixture preferably includes at least one liquid surfactant and at least one lipid. The lipid is preferably selected from the group of emollients, lubricants, medicaments and skin protectants. A method for forming said impregnated matrix is further provided as is a method for applying a lipid emollient, lubricant, medicament and/or protectant mixture to skin.
The present invention relates to a substantially dry matrix or matrix of the type which is described, for example, in U.S. Pat. No. 5,091,102, the disclosure of which is hereby expressly incorporated herein by reference thereto. Such matrix is substantially dry and is devoid of any water other than the water which may be naturally present in the matrix as manufactured and the matrix remains dry to the touch after impregnation with the treatment mixture. A typical matrix for use in the present invention is a cellulosic material, which while dry to the touch, may contain up to about 3% water.
As used herein, the term matrix may further include the finished matrix, cloth or towel product, i.e., a wipe, garment, etc.
A useful matrix may contain natural or synthetic fibers, processed into woven, non-woven or knitted form, a flexible foam, or combinations thereof, in a basis weight range generally of between 5 and about 200 grams per square yard and preferably between 15 and about 100 grams per square yard. A preferred matrix is comprised of woven or non-woven thermoplastic filaments or fibers, preferably of polypropylene, with a basis weight range of between about 5 and about 100 grams per square yard, preferably between 15 and 40 grams per square yard. The tensile strength of such a matrix must be sufficient to enable the wipe to be used without shredding or disintegrating and should generally be between about 0.5 and about 1.5 pounds per inch of width. The matrix can consist of a single layer of the filaments or fibers or a foam layer or it can consist of a plurality of layers of the same filaments or fibers and/or foam which have been adhered by using any suitable method such as sonic, thermal or mechanical bonding, etc. Final selection of the matrix will of course, depend upon its actual intended application.
Particularly preferred matrices include fibers selected from the group consisting of polypropylene, polyester, nylon and cellulosics, such as cellulose, cotton, rayon, hemp, etc. and foams selected from the group consisting of polyurethane, polypropylene, polyethylene, polyester, etc.
A treatment mixture preferably consists of at least one surfactant and a lipid emollient, and/or protectant, and/or a medicament, and/or lubricant. The treatment mixture is applied to the matrix and impregnated therein. When the matrix is applied to skin, the lipid is readily transferred thereto and remains on the skin as a film. In another aspect of the present invention, when the matrix is exposed to water at the point of use and pressure is applied by squeezing, or rubbing, the matrix, the treatment mixture forms an unstable emulsion which maybe adapted to release the lipid onto the skin.
The treatment mixture preferably includes a glycol, and more preferably propylene glycol. USP, although any glycol which is safe, nontoxic and possesses the ability to coat fibers uniformly may be used. The glycol used desirably imparts a softness to the dry matrix. The glycol may act as a non-ionic liquid surfactant, or in any other conventional capacity for which glycol is used in the cosmetic and pharmaceutical industries.
Polyethylene glycol and CARBOWAX(copyright) (methoxy polyethylene glycol), may also be used in the present invention. These compounds are members of a family of linear polymers formed by the addition reaction of ethylene oxide. The generalized formula for polyethylene glycol is
HOxe2x80x94(CH2CH2O)nxe2x80x94H
and for the methoxy polyethylene glycol is:
CH3Oxe2x80x94(CH2CH2O)nxe2x80x94H
wherein xe2x80x9cnxe2x80x9d is the average number of repeating oxyethylene groups. The repeating ether linkages and terminal hydroxyl groups give rise to the water solubility of the polyethylene glycol.
Polyethylene glycol is generally available in average molecular weights ranging from 200 to 8000 and methoxy polyethylene glycol is available is average molecular weights ranging from 300 to 5000.
The treatment mixture typically contains a glycol in an amount between 1% and about 99% by weight of the treatment mixture and, preferably, between about 4% and about 50% by weight.
The treatment mixture optionally also contains other nonionic and cationic surfactants, either separately or in combination. The cationic and nonionic surfactants described in U.S. Pat. No. 5,091,102, the disclosure of which is hereby incorporated herein by reference, may be used in the present invention. Preferred cationic surfactants can be selected from any of the well-known classes of water soluble quaternary ammonium compounds. Such classes include the quaternary heteronium3 compounds such as cetyl pyridinum chloride and polymeric quaternary compounds of the general formula:
3 The term xe2x80x9cheteronium compoundxe2x80x9d is defined in Hackh""s Chemical Dictionary, 4th Edition, as a xe2x80x9chetero-prefix (Greek) indicating unlikeness or differencexe2x80x9d and xe2x80x9conium-suffix and indicating a complex cation . . . xe2x80x9d
wherein R1 and R2 are selected from an alkyl group, an alkyl ether group and a hydroxyalkyl group each containing from 1 to 3 carbon atoms. R3 is an alkyl group containing from 6 to 20 carbon atoms, and R4 is selected from an alkyl group containing 6 to 20 carbon atoms, an aralkyl group wherein alkyl contains 1 to 2 carbon atoms and heterocyclic radicals and X is a suitable anion such as halide, e.g., chloride, bromide and iodide or nitrate, methosulfate or acetate.
A particularly useful compound having the general formula listed above is one wherein R and R1 and R2 are alkyl groups having 1-3 carbon atoms, R3 is an alkyl benzyl group such as dodecylbenzyl, R4 is a polypropylene oxide group, and X is chloride.
Particularly useful quaternary ammonium compounds of the above-indicated general formula are the C8-18 alkyl dimethyl ammonium chlorides and mixtures thereof.
Examples of such cationic surfactants which may be used include: Stepan BTC2125M or BTC 65.
The preferred amount of cationic surfactants compound to be included in the treatment mixture in accordance with the present invention ranges between about 0.5% and about 50% by weight, and preferably is between about 1% and about 25% by weight.
The preferred glycol compounds themselves exhibit nonionic surfactant properties. In addition, however depending upon the specific end use to which the matrix is to be put, the mixture may also be optionally contain up to about 0.5% to 50% by weight of another nonionic surfactant in addition to the glycol specified herein. Suitable nonionic surfactants include those selected from the group consisting of:
(a) the polyethylene oxide condensates of alkyl and dialkyl phenols, having a straight or branched alkyl group of from about 6 to about 12 carbon atoms with ethylene oxide, wherein the amount of ethylene oxide present is from about 3 to about 25 moles per mole of alkyl phenol;
(b) the condensation products of aliphatic alcohols with ethylene oxide of the formula RO (C2H4O)nH and/or propylene oxide of the formula RO (C3H6O)nH: wherein in either or both cases R is a straight or branched alkyl group having from about 8 to 22 carbon atoms, and n is 3 to 40;
(c) polyoxyethylene polyoxypropyl block polymers.
When employed in accordance with the present invention, the nonionic surfactant la be present in the treatment mixture in an amount up to about 50% by weight of the treatment mixture and, preferably, in an amount between 0.5 to 50% and most preferably about 5% and about 40% by weight of the total mixture.
The surfactant composition used in the dry matrix of the present invention may alternatively comprise a non-ionic and an anionic surfactant.
It is also desired that the surfactant composition used in the dry matrix of the present invention has a hydrophilic-lipophilic balance between about 4 and 11.
As previously stated, the treatment mixture further contains a lipid which can be one or more members of the group of emollients, lubricants, surface protectants, and medicaments for transfer to the skin surface.
Useful emollients include stearyl ethers and caproic esters. Emollients serve to soften skin. A 5 particularly preferred emollient is a caprylic/caproic ester, most preferably the product sold by HULS America under the trademark MYGLIOL:8124
4 insoluble in water.
The emollient should be included in the treatment mixture in an amount between about 5% and about 70% by weight of the treatment mixture and, preferably, in an amount between about 20% and about 40%.
Useful lubricants include mineral oil5 petrolatum6 and wax7. Lubricants serve to protect skin and prevent moisture loss. They also function as humectants. A particularly preferred lubricant is mineral oil and, most preferably, the mineral oil product sold by J.T. Baker under the trademark Mineral Oil USP. The lubricant may be included in the treatment mixture in an amount between about 1% and about 50% by weight of the treatment mixture and, preferably, in an amount between about 1% and about 15%.
5 Insoluble in water.
6 Insoluble in water.
7 Insoluble in water.
Useful protectants include the polysiloxanes8, dimethicone9 and cyclomethicone10. A particularly preferred protectant is demethyl polysiloxane, and most preferably, the silicone product sold by General Electric, under the trademark Silicone Fluid SF96-350.
8 Insoluble in water.
9 Immiscible in water.
10 Immiscible in water.
The protectant, when so included, should comprise between about 5% and about 50% by weight of the treatment mixture and, preferably, be present in an amount between about 10% and about 25%. It will be appreciated, however, that the actual amount of protectant will vary depending upon the particular protectant and the application.
In a similar manner, medicaments such as, for example, zinc oxide11, aloe, titanium dioxide12, sulfadiazine13, sulfaguanidine14, citronellol15 and the like can also be included for application to the skin surface. Other pharmacological agents that could be included would be (a) vitamins A, C, D, E16 etc. (b) antimicrobials such as bacitracin, neomycin, miconazole, oxyquinoline, polymycin, and the like, (c) anti-inflammatory agents such as steroids, (d) antihistamine agents such as benadryl, (e) anti-acne agents such as salicylic acid or retinoic acid17 etc.
11 Insoluble in water.
12 Insoluble in water.
13 Sparingly soluble in water.
14 Sparingly soluble in water.
15 Very slightly soluble in water.
16 Insoluble in water.
17 Insoluble in water.
It will of course be appreciated that the treatment mixture may contain the lipid emollients, lubricants, protectants, and medicaments, either singularly or in combination, depending upon the particular application.
In order to prepare an impregnated matrix, a treatment preparation is made by strongly agitating the components. This preparation is added to the matrix.
The matrix may be prepared in the manner described in U.S. Pat. No. 5,091,102. Commercially manufactured matrices may also be used such as, for example, DuPont""s Sontara matrix which consists of a mixture of cellulosic and synthetic fibers normally supplied in a basis weight of 62 grams per square yard.
The matrix is then coated with the treatment mixture using a conventional transfer process such as, for example, the process described U.S. Pat. No. 5,091,102. In such process, continuous rolls of the matrix are passed between an engraved roller and a smooth roller under pressure. The engraved roller includes a plurality of cells and cavities that are defined by specific shape and dimensions. During operation, the engraved roller is partially submerged in the treatment mixture and rotates there through causing the mixture to fill the cavities of the engraved portions of the engraved roller. Excess mixture which may accumulate is removed by a doctor blade. The mixture remaining in the cells of the engraved roller is transferred by way of pressure absorption and surface tension into the matrix as it passes under pressure between the engraved roller and smooth roller. It will, of course, be appreciated that the treatment mixture may also be applied to the matrix by other treatment methods such as spraying, dipping, extrusion or reverse rolls.
The treated matrix containing the predetermined measured volume of treatment mixture may be wound onto rolls and/or is converted into the desired product.
The xe2x80x9cwater-freexe2x80x9d treated matrix is dry to touch on fabrication, no separate drying step being required to dry the same.
The impregnated or treated matrix may then be used for direct application of the emollient. Lubricate, medicament and/or surface protectant to the skin. When such matrix is placed in contact with the skin, the lipid is transferred out of the matrix and onto the skin in the form of a thin film Furthermore, when the treated matrix is exposed to eater at the point of use and sufficiently squeezed, or rubbed, the glycol, surfactants and emollient, protectant, medicament and/or lubricant substantially instantaneously form an emulsion with the water, which can transfer the lipid to the skin surface.
It will be appreciated that the treated or impregnated matrix containing non-aqueous components can be composed of one layer or multiple layers.
When the matrix or wipe of the present invention is first treated with the mixture of partially water and oil soluble surfactants and emollients, antimicrobial agents, lubricants and/or medicaments, at least one of which is a lipid, the lipid material is believed to be absorbed on the lipophilic portion of the fibers composing the matrix and spreads to form a thin film. When the treated wipe is contacted with water at the point of use, the aqueous phase is also absorbed by the hydrophilic portion of the fibers and spreads to form a thin film. However, the emulsion does not form (to any substantial degree) until (shear) energy (rubbing) is applied to mix the matrix surfaces. The two immiscible phases are both present absorbed on the surfaces of the fibers as high surface area films in close contact. Rubbing the matrix or treated wipe on skin, creates sufficient shear energy to overcome the viscous resistance of the liquids and disperses the oil phase in the aqueous phase creating an instant emulsion. The emulsion transports the lipid material to the skin surface. Once the shearing action stops, the emulsion breaks and the phases once again separate on the matrix fiber. The emulsion reforms when energy, i.e. rubbing, resumes. It should be noted that without the emulsion, the lipid remains on the matrix.
In an alternative application of the treated matrix of the present invention, the matrix is moistened and rubbed just before use to form an unstable emulsion that is effective to transfer a lipid to a skin surface when the skin is wet.
An emulsion is a dispersion of a first liquid in a second immiscible liquid. Since most emulsions contain water as one of the two phases, emulsions are usually classified as either an oil-in-water (O/W) emulsion having droplets of oil dispersed in a continuous water phase, or a water-in-oil (W/O) emulsion having droplets of water dispersed in a continuous oil phase. The continuous liquid, or phase, is referred to as the dispersion medium, and the discontinuous liquid, or phase, is the disperse phase.
One cannot prepare a stable emulsion of two pure immiscible liquids. Rather, an emulsion requires a third component: an emulsifying agent or surfactant. Generally, adding a surfactant lowers the interfacial tension of the two phases which allows an emulsion to form when the two immiscible liquids are mechanically agitated. During agitation, both liquids form droplets with one of the liquids becoming continuous and the other remaining in droplet form when an emulsifier (a stabilizing compound) is included in the agitated mixture. However, if this mixture of droplets does not include the emulsifier, the droplets will separate into two phases when the agitation ceases.
The type of emulsion, O/W or W/O, is determined in part by the volume ratio of the two liquids, provided the ratio is sufficiently high. For example with a 5% water and 95% oil volume present (an oil to water phase ratio 9), the emulsion will be a W/O type. For moderate ratios (between about 0.3 and 3), the type of emulsion is determined by several such as the order of addition and the type of emulsifier. One liquid slowly added to the other with agitation usually results in the last added phase being the continuous one. Moreover, the phase in which the emulsifier is most soluble is generally the continuous phase. For example, water soluble soaps stabilize oil-in-water emulsions whereas water insoluble soaps stabilize water-in-oil emulsions.
Emulsification creates new surfaces between the two phases, namely the surfaces between the droplets. Such surface creating processes require energy: the surface free energy. Numerically, the surface free energy is identical to the surface tension. However, most of the energy consumed during emulsification is used to overcome the viscous resistance of the liquids during agitation, and not to enlarge the interface. As a consequence, low viscosity liquids are easier to emulsify than high viscosity fluids. Based on this observation, it is preferred that the viscosity at 25xc2x0 C. of the lipid material used in the present invention is less than about 300 cps.
Through the use of agitation or shear forces, emulsification usually breaks the original phases into progressively smaller droplets. Variations in the mode of agitation, the nature and amount of emulsifying agent, pH and temperature changes also affect emulsification.
Commercial applications usually require emulsions to be stable for months, if not longer But, how stability is defined, and how it is measured, depends upon the specific application. Nonetheless, when an emulsion breaks down, the dispersed droplets coalescence, or flocculate. During flocculation, droplets combine into large droplets until finally the droplets achieve an observable separate phase. A fully separated emulsion consists of separate oil and water layers.
Both the charge at the interface and the packing of the emulsifier molecules effect the stability of an emulsion. Emulsions with a small average droplet size are more stable. For this reason, commercial emulsions are often prepared with homogenizers that rapidly reduce droplet sizes.
While a low viscosity makes emulsification easier, a high viscosity retards flocculation, and thus improves the emulsion""s stability.
The treated matrix of this invention is impregnated with a mixture of a liquid surfactant and a lipid, which preferredly is a skin protectant, antimicrobial agent and/or emollient.
In an alternative embodiment, directly before use, at least about three parts, by volume, of water is added to each part, by volume, of the treated matrix. The towel is then rubbed on skin. This rubbing provides sufficient shear and agitation to uniformly disperse the lipid phase in the water phase which facilitates the transfer of the active ingredients to the skin surface. To achieve this instant emulsion under low shear conditions of the type encountered when the skin is rubbed with a wipe, sufficient surfactant that is partial solubility in both phases must be present to reduce the interfacial tension and facilitate the substantially instantaneous formation of the emulsion. In addition, the viscosity of the dispersed and continuous phase are desirably kept low by using a lipid with a low viscosity. Such lipids readily emulsify upon application of xe2x80x9crubbingxe2x80x9d shear. While this emulsion breaks when the matrix is quiescent (i.e., when the rubbing stops), it reforms with further rubbing.
To achieve the instant emulsion under low shear of this invention, the surfactants are desirably present in an amount of at least about 15% by weight of the lipids, and preferredly between about 15 and 50% by weight. These surfactants also should exhibit partial solubility in both the continuous phase (here, water) and dispersed phase (here, lipid) so that the interfacial tension is quickly reduced.
Unlike pre-prepared stable emulsions encountered in commercial products heretofore, the stability of this in situ formed emulsion once the rubbing (aggitation) stops is not important. In a preferred embodiment of the present invention, the uniformly dispersed emulsion only exists while the matrix is being agitated, i.e., rubbed. Nonetheless, this short lived emulsion is effective to transfer the disperse phase from the matrix to the rubbed skin surface.
Ordinarily, the low shear created by rubbing a treated wipe on a skin surface is insufficient to emulsify two immiscible liquids, particularly when the two insoluble liquids are in a test tube or mixing tank. The success of this invention is based on the substantially instantaneous creation of the emulsion on the fibers of the treated matrix. There, the two liquid phases exist as thin films coating the matrix fiber surface, which results in a high surface area films. In the presence of surfactants, these high surface area thin films mix intimately and emulsify under low shear.
The invention will be illustrated by the following examples which are not to be construed in limitation thereof:

Impregnated matrix and method for making same

Unilever Home and Personal Care USA, division of Conopco, Inc.